The Mushroom Hill Zone is a Zone on the Floating Island. A lush, forested area filled with giant mushrooms, it became the home of the Emerald Hill folk when they fled from the wrath of Doctor Robotnik. The citizens hollowed out the mushrooms and made them their homes, seemingly quite happy with their new lives.
The Zone is fairly close to the edge of the island, yet a Zoom tube linking to the Emerald Chamber allows Knuckles the Echidna to watch over his guests. Once Robotnik was desposed, the people of the Zone demanded to be returned home, leaving the Zone abandoned.